Only one trouble: With the space shuttle fleet retired, NASA doesn't have its own spaceship to fly astronauts and is sending fewer of them into orbit.

Gallery: Space Shuttle Lands at NAS JRB

But with veteran astronauts leaving the space agency, NASA's flight crew chief says the agency is afraid it will not have enough astronauts. So in front of dozens of elementary school students, NASA on Tuesday unveiled its biggest ever public push to hire new astronauts.